This invention relates to X-ray tubes, in which an anode assembly and a cathode assembly are positioned in a vacuum-tight manner to an evacuated envelope. The anode assembly is secured by a glass seal to one end of the envelope and a cathode assembly is secured by a glass seal ring to the other end of the envelope. The anode and cathode assemblies face each other at a predetermined distance. The cathode assembly includes filament for emitting electrons which are accelerated toward the anode. The anode assembly, includes an angled tungsten target, and an anode block. The target is located at the center of the end of the target block such that it faces the filament of the cathode assembly. A window member made of an X-ray transmitting material may be provided on the envelope and in a position on the envelope adjacent the anode.
In the operation of such X-ray tube, the electrons emitted from the filament are accelerated by a voltage applied between the anode and cathode. The accelerated electrons impinge on the angled target to form a spot thereon. The angled target emits X-rays which are radiated through the window as an X-ray field emission.